Diarra hopes the move south will guarantee first-team football

The 22-year-old French international has joined Pompey on a three-and-a-half year contract for an undisclosed fee.

"In my opinion, he's already one of the best midfield players in the Premier League and has the ability to be one of the best there is.

"I'm delighted he has decided to sign for us rather than a host of other clubs," said Redknapp.

"He's strong, powerful, quick and can pass the ball - you don't play for France for the last nine or 10 games unless you're top quality."

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Diarra is Redknapp's first signing since turning down the chance to manage Newcastle and his arrival will help compensate for the absence of a number of key players at the Africa Cup of Nations, including midfielders Sulley Muntari and Papa Bouba Diop.

He first came to England to join Chelsea, but moved on to Arsenal last August in a £2m deal.

The switch to the Emirates Stadium did not, however, bring him regular first-team football.

And he believes Portsmouth will give him the opportunity to secure his place in France's Euro 2008 squad.

"My choice could shock and surprise people, I am conscious of that. But I know the Portsmouth manager, I know he is going to play me," the French newspaper L'Equipe quoted Diarra as saying.

"I need to play. I really want to think about myself, about those who appreciate me, who want to see me a little more on the pitch.

"I am 22 and the most important thing for me is football, my job, my passion.

"I read that the club [Arsenal] wanted to keep me. But when you want to keep someone, you do it by playing them. This hasn't been the case.

"Some are already saying that in going to Portsmouth, I am making a mistake regarding my chances with Les Bleus [France], but I don't think so. I have thought about it."